I am in no way saying you don't have a point about the lift/propel dilemma, mostly just pointing out that someone out there probably has a build/character that they do well with that's outside of what would be considered the norm. As in this case I love my Dominator and do very well with him.
I have a level 50 Gravity/Dark Dominator with Perma Domination and Softcapped range defense, I do not have lift in my build. I love this toon and have a blast playing him, He feels quite powerful to me, and I have no issues playing him. It took quite a while to get the build "right" A big part of it is the perma domination, its one of the best inherent powers in the game as far as I am concerned.
It has the following effects. Quoted form the wiki "Your control powers will typically last 50% longer and will more easily Dominate stronger opponents. Additionally, you will completely recover your Endurance" "Domination protects the villain from Knockback/Knockup, Repel, Disorient, Hold, Sleep, Immobilize, Fear, and Confuse effects, and can be activated even while suffering from them to break the villain free." "Domination doubles the magnitude of the villain's own Disorient, Hold, Sleep, Immobilize, Fear, and Confuse effects for their normal durations, then keeps them going at normal magnitude for half that amount of time longer."
In Short I get a constant flow of Endurance to help balance out the high end usage of Dark Assault, I have constant status effect protection, my Mez are stronger and last longer, and with soul mastery as my patron powers I have a few area effect damage powers. Dark Obliteration, NightFall, Souldrain, Dark Consumption, and Engufling Darkness. Now the last three are PBAOE, but once things are held/stunned its not an issue to get in close to pop one or two off. Furthermore with Sudden acceleration knockback to knockdown slotted in wormhole its quit the handy/fun power. Oh and I love Propel its such a unique power, maybe not the best or most efficient. It is better that it used to be and quite fun to use.
For me the reason to play a Dominator vs a Controller is partly about the range damage potential from the Assault set, part of it is thematic, and the biggest part is how amazing domination is. With softcaped range def and mez protection he does not die often which is fun and more efficent. As I have him built he can stay in the back or flying above and use range attacks, and occasionally move in close when its safe to hit his PBAOES.
Just kind of throwing out there my build and why I have a dominator vs a controller with gravity control. Not saying I would be against some kind of fix, but for me I just sidestepped some of the issue altogether by not taking lift, its a power in the set that I have never cared for. So for me honestly my issue is more with lift than propel, I would not mind if propel did some AoE damage in addition to its AoE knockdown, that would make up some for its slow cast time I think. Lift, well I don't know, its slow cast/animate time was a big enough issue for me that I skipped it entirely.